[Python-ideas] Inline assignments using "given" clauses

Rhodri James rhodri at kynesim.co.uk
Fri May 11 07:37:43 EDT 2018

On 11/05/18 11:14, Jacco van Dorp wrote:
> 2018-05-11 11:56 GMT+02:00 João Santos <jmcs at jsantos.eu>:
>> Optimizing syntax for space makes sense for "mathematical" notation since
>> it's commonly written by hand, but putting space above readability in a
>> programming language design feels like a skewmorphism.
> You are assuming "given" to improve readability, where I stated ":= is
> perfectly clear ", at least in my opinion. Therefore, since clarity is
> already achieved, the rest is clutter that reduces readability.

I respectfully disagree with your opinion (i.e. you're wrong :-)


   while (cmd := get_command()).token != CMD_QUIT:


   while cmd.token != CMD_QUIT given cmd = get_command():

I find I write code like this[*] a fair bit, since my major use for 
Python is to write remote monitors for embedded kit, so it's pretty much 
a real world example.  I don't find the first version using ":=" to be 
perfectly clear, in fact I think it's rather ugly.  That may be partly 
the same reaction that many of us had to the asymmetry of assignment 
expressions in (over-)complicated comprehensions.  The second version 
using "given" reads much more naturally to the mathematician in me, and 
not too badly to my English half either.

[*] By "like this" I mean the clunky "while true:" spelling, obviously.

Rhodri James *-* Kynesim Ltd

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